Signal feedback from a sound adjustment for noise compensation in a vehicle sound system

Abstract

The invention relates to a control unit for a vehicle for specifying a level of an audio signal for a loudspeaker unit (1) in the vehicle, comprising a module (3) designed as a VNC module for determining a target level for compensating ambient noise, and comprising a sound adjustment unit (5) for generating a desired sound image of the loudspeaker unit (1) by adjusting the audio signal, wherein a signal feedback (7) is provided from the sound adjustment unit (5) to the module (3), which transmits information about a current adjustment of the audio signal by the sound adjustment unit (5) to the module (3), and wherein the module (3) is designed to adjust the target level depending on the information about the current adjustment by the sound adjustment unit (5).

Description

[0001] The invention relates to a control unit for a vehicle for specifying a level of an audio signal for a loudspeaker unit in the vehicle, and a method for specifying a level of an audio signal for a loudspeaker unit in the vehicle.

[0002] Methods for adjusting the volume control of sound systems for vehicles, particularly in relation to speed, are known from the prior art.

[0003] US Patent 5,034,984 A relates to a variable-gain amplifier that receives an electrical input audio signal; its gain is controlled by a vehicle speed signal representative of the vehicle's speed. The signal supplied by the variable-gain amplifier is coupled to a manually adjustable volume control, which is coupled to a power amplifier that drives a loudspeaker. According to a specific formulation, the manually adjustable volume control is an element in a dynamic equalization circuit that changes the equalization in the bass frequency range, typically below 200 Hz, in accordance with the control's setting, to provide more gain at lower volume control settings.

[0004] US Patent 4,944,018 A further relates to a vehicle with an engine and a sound amplification system characterized by a frequency response comprising a signal source and a manually operated sound level control that sets the sound level of the desired signal in the vehicle, a power amplifier, and an electroacoustic transducer. The manually operated sound level control includes a dynamic equalization circuit for providing a predetermined equalization over the bass frequency range depending on the sound level setting of the sound level control. A variable gain device connected to the sound level control responds to an input electrical audio signal, which is to be amplified by the system to provide a signal with a controlled amplitude.

[0005] EP 1 401 243 A1 relates to a method for optimizing an audio signal comprising the following steps: a) Continuously determining the difference between a predetermined audio signal and a modified audio signal resulting from the predetermined audio signal, wherein the difference is determined in the time domain and / or the frequency domain, and b) Continuous determination of an optimized audio signal using the difference in the time domain and / or frequency domain.

[0006] DE 60 2004 004 242 T2 further relates to an arrangement for improving an audio signal for compensating for ambient noise in a listening environment, comprising the following: an audio signaling device for generating an electrical sound signal and generating a sound output from said electrical sound signal; a sensor for obtaining an overall sound signal characteristic of the overall sound level in said environment, wherein said overall sound level includes both said sound output from said audio signaling device and the ambient noise within said environment; an extraction device that responds to said overall sound signal and to said electrical sound signal in order to extract an ambient noise signal from the ambient noise in said environment from said overall sound signal;a control device that responds to said ambient noise signal to perform a Linear Predictive Coding (LPC) analysis and generate a control signal based on the result of said analysis; and an equalization device that responds to said control signal to adjust the sound output of said audio signaling device to compensate for said ambient noise level, characterized in that a psychoacoustic filter responding to said ambient noise signal generates a weighted ambient noise signal that is provided to the control device.

[0007] DE 197 34 969 A1 relates to a device for playing back audio signals, which has a pitch control device for increasing or decreasing the gain of the audio signals in one or more defined frequency ranges of a frequency curve of the audio signals and a volume control device for increasing or decreasing the gain of the audio signals in a full effective frequency range of the frequency curve of the audio signals, wherein the pitch control device reduces the gain in the defined frequency ranges when the gain of the audio signals in the full effective frequency range is increased by the volume control device, and the pitch control device increases the gain of the audio signals in the defined frequency ranges when the volume control device decreases the gain of the audio signals in the full effective frequency range.wherein an additional gain component can be applied to the frequency curve in at least one of the defined frequency ranges by means of the pitch control device.

[0008] DE 198 32 472 A1 also relates to a method for influencing an audio signal depending on ambient noise in a playback room in which the audio signal is emitted via at least one loudspeaker, wherein predetermined frequencies and / or predetermined frequency bands of the audio signal are selectively amplified and / or attenuated depending on the ambient noise.

[0009] DE 102 51 188 A1 also relates to a control circuit for an audio amplifier, comprising an input for a sound level measurement signal, an input for at least one sound level-correlated signal, and an output for a setpoint signal representing a desired gain of the audio amplifier, a storage unit for storing a functional relationship between signal levels applied to the inputs of the control circuit, a learning unit for recording the functional relationship, and a control unit for setting a level of the setpoint signal based on a level of the at least one sound level-correlated signal and the functional relationship, and outputting the setpoint signal level at the setpoint signal output.

[0010] Such compensatory volume and / or sound adjustments (also called "vehicle noise compensation," abbreviated 'VNC') are widely used. Improved noise compensation results are achieved when additional factors beyond vehicle speed are considered. These include the engine speed and microphone signals detecting ambient noise in the vehicle interior. Based on the functional relationships of these influencing factors as input, target values ​​for volume and sound correction are determined and applied, typically incorporating the manually set volume level into the calculation of these target values.

[0011] Modern vehicles often feature more than just a set volume level that results in a defined sound level. Special modes like stereo and 3D sound, as well as equalizer settings, generally cause slight level fluctuations even when the set volume remains constant. If these level fluctuations are used as input for a module that compensates for volume and / or sound adjustments—for example, because the level of an audio source or file is also taken into account—the system can over- or undercompensate, and the target values ​​for volume and sound correction described above will no longer achieve the desired result. A vehicle occupant perceives this as follows: - as overcompensation: Audible fluctuation in volume and tone; - as undercompensation: the sound appears too quiet to the occupant depending on the driving situation, e.g. during acceleration and when driving fast.

[0012] The object of the invention is to avoid such over- and undercompensation.

[0013] The invention is defined by the features of the independent claims. Advantageous further developments and embodiments are the subject of the dependent claims.

[0014] A first aspect of the invention relates to a control unit of a vehicle, which is configured to generate an audio signal for a loudspeaker unit in the vehicle, wherein the control unit has a module configured as a VNC module and serves to determine a target level of the audio signal for compensating for ambient noise, and wherein the control unit has a sound adjustment unit for generating a desired sound image of the loudspeaker unit by adjusting the audio signal, wherein a signal feedback is provided from the sound adjustment unit to the VNC module, which transmits information about a current adjustment of the audio signal by the sound adjustment unit to the VNC module, and wherein the VNC module is configured to adjust the target level depending on the information about the current adjustment by the sound adjustment unit.

[0015] The intended signal path is as follows: Data stored digitally or received via a network is read from a data source, and a corresponding audio signal derived from this data contains the information necessary to achieve sound reproduction at a speaker unit in the vehicle, based on the data from the source. This signal path incorporates the implementation of a user-defined volume setting by adjusting the overall level of the audio signal accordingly. Furthermore, this signal path includes a VNC module for determining a target level to compensate for ambient noise. This ambient noise is generated, for example, by the rolling of the vehicle's wheels, aerodynamic effects from the airflow around the vehicle, engine noise, etc.To compensate for these ambient noises, the module uses corresponding influencing factors, which can be recorded and, in particular, measured in real time.

[0016] Such influencing factors can include vehicle speed, engine speed, a measured sound level (particularly calculated by differentiating the sound from the loudspeaker unit), a measured sound level on an exterior surface of the vehicle, or other factors. For this reason, the module is often referred to in the prior art as a VNC module, where VNC is an abbreviation for "vehicle noise compensation".

[0017] Separately from the VNC module, a sound adjustment unit is provided, which serves to set a desired sound profile at the loudspeaker unit. For this purpose, the audio signal is adjusted, particularly depending on the frequency. One example of a possible sound adjustment unit is an equalizer, another is a surround sound upmix. To achieve frequency-dependent sound level control in a sound system, this so-called equalizer is typically used. This makes it possible, in particular, to define the distribution of the sound level across highs, lows, etc., i.e., the amplitude distributions of adjacent frequency bands within a certain frequency range. Since the amplitudes of the frequency bands are adjusted, the current setting on the equalizer generally also affects the overall sound level of the audio signal and thus the overall volume of the output sound.In addition to an equalizer, other sound processing methods can also be used to influence the sound.

[0018] The VNC module adjusts the audio signal level according to these influencing factors. This adjustment can also be frequency-dependent, giving the VNC module its own built-in equalizer, which is primarily time-dependent. Additional sound effects can also be applied via the VNC module, but these are generally dependent on the current influencing factors. In contrast, the audio signal adjustment at the sound adjustment unit is based on a user's manual input.

[0019] Preferably, the VNC module is connected upstream of the sound adjustment unit to specify a target level for the audio signal, depending on the parameters of the unit. The sound adjustment unit itself then performs adjustments to the audio signal, which, however, constitutes a signal level-altering processing of the audio signal for the vehicle's speaker unit. This can lead to the overcompensation or undercompensation in the VNC module described earlier.

[0020] To prevent these issues, a feedback loop is provided from the sound adjustment unit back to the VNC module. This allows the VNC module to adjust the target level based on the sound adjustment unit's settings, thereby compensating for any level-altering effects of the sound adjustment unit. The feedback loop transmits one or more correction factors, particularly for a modified amplitude of the audio signal, and in a further implementation, one or more correction factors for the frequency of the audio signal, to the VNC module, or generates these factors from the information there.

[0021] This also advantageously takes into account downstream factors influencing volume, such as the aforementioned equalizer or other sound processing methods, particularly in the speed-dependent volume and sound adjustment of the VNC module for compensating speed-dependent driving noise in vehicle sound systems. These downstream factors generally have a negative impact on the correct execution of the volume control, in the form of over- or undercompensation, but are advantageously addressed by the feedback loop.

[0022] According to an advantageous embodiment, the current adjustment includes an adjustment of a frequency-dependent level.

[0023] According to another advantageous embodiment, the sound adjustment unit includes an equalizer.

[0024] According to a further advantageous embodiment, the information about the current adjustment includes a frequency-dependent level adjustment by the sound adjustment unit, wherein the VNC module is designed to specify the target level in a frequency-dependent manner.

[0025] According to a further advantageous embodiment, the VNC module for compensating ambient noise comprises a microphone, wherein the VNC module is designed to use a sound level detected by the microphone in the vehicle to specify the target level.

[0026] According to another advantageous embodiment, an input signal of the sound adjustment unit is an output signal of the VNC module.

[0027] Another aspect of the invention relates to a method for generating an audio signal for a loudspeaker unit in the vehicle, wherein a target level of the audio signal for compensating ambient noise is determined by a module designed as a VNC module, and wherein a desired sound image of the loudspeaker unit is generated by a sound adaptation unit by adapting the audio signal, wherein a signal feedback from the sound adaptation unit to the VNC module is used, which transmits information about a current adaptation of the audio signal by the sound adaptation unit to the VNC module, and wherein the target level is set by the VNC module depending on the information about the current adaptation by the sound adaptation unit.

[0028] According to another advantageous embodiment, the VNC module generates an output signal which is adapted by the sound adjustment unit and, after adaptation, is transmitted to the loudspeaker unit.

[0029] According to another advantageous embodiment, an input signal of the VNC module is formed from an audio data stream and a volume setting adjustable by a user.

[0030] According to another advantageous embodiment, the VNC module performs a compensation of a frequency-dependent level that depends on the vehicle speed.

[0031] Advantages and preferred further developments of the proposed procedure result from an analogous and substantive transfer of the above statements made in connection with the proposed control unit.

[0032] Further advantages, features and details will become apparent from the following description, in which - possibly with reference to the drawing - at least one embodiment is described in detail.

[0033] It shows: Fig. 1: A control unit according to an embodiment of the invention.

[0034] Fig.Figure 1 shows a control unit for generating an audio signal for a loudspeaker unit 1 in a passenger car. The left half of the figure symbolically represents a data source. For example, data from a radio, internet radio, a data storage device installed in the passenger car, or a mobile data storage device carried in the passenger car is provided digitally in a data stream, for instance, to enable music playback at the loudspeaker unit 1 of the passenger car. The vehicle also includes an input device that allows a user, particularly a passenger, to set the volume level. Using this input device, the user can generally adjust the sound pressure level in the vehicle's interior to their liking. The data stream from the data source corresponds to the audio signal and its level is adjusted accordingly.To compensate for road noise, a module 3 is provided in the signal path between the data source and the loudspeaker unit 1. This module uses influencing factors, such as those from a microphone 9, to determine a compensation level. This is achieved, for example, to offset increasing road noise with increasing speed by increasing the sound level in the audio signal. The microphone 9 is just one example of an influencing factor; additional or alternative influencing factors can be used in addition to the microphone 9 signal, such as just the vehicle speed. The module 3 adjusts the level of the audio signal based on the current vehicle speed and also modifies the levels across individual frequency bands.Downstream of Module 3 is a sound adjustment unit 5, which in this example, but not limited to this one, includes an equalizer and / or other sound enhancement elements. For example, if a sound enhancement is changed from stereo to 3D sound and / or frequencies in a bass range of the audio signal are amplified in the equalizer of the sound adjustment unit 5, information about this change is transmitted to Module 3 via a signal feedback loop 7. Module 3 thus receives a feedback signal about the effect of the sound adjustment unit 5. This feedback signal in the signal feedback loop 7 is used in Module 3 to determine a correction factor, at least for the target level. This represents the simplest case, in which only the level level, in the form of the target level, is changed for all frequencies.However, it can also be provided that a frequency-dependent correction takes place in module 3, particularly if the audio signal is manipulated in a frequency-dependent manner in the sound adjustment unit 5. This measure advantageously prevents over- or undercompensation from occurring when a passenger in the vehicle uses different sound settings than those for which module 3 was designed. Overcompensation, in particular, leads to a perceptible adjustment, where an audible fluctuation in volume occurs during acceleration or deceleration of the vehicle. Undercompensation occurs when the implementation of module 3 contains a suboptimal mapping to the target level. The problem of over- and undercompensation can be solved by the signal feedback 7 and the information about which levels are currently being adjusted by the sound adjustment unit 5.

[0035] Although the invention has been further illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned as examples are truly only examples and are not to be understood in any way as limiting, for example, the scope of protection, the possible applications, or the configuration of the invention.Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without leaving the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description. Reference symbol list 1 speaker unit Module 3 5 Sound adjustment unit 7 Signal feedback 9 microphone

Claims

[1] Control unit of a vehicle configured to generate an audio signal for a loudspeaker unit (1) in the vehicle, wherein the control unit has a module (3) configured as a VNC module and serves to determine a target level of the audio signal for compensating for ambient noise, and wherein the control unit has a sound adjustment unit (5) for generating a desired sound image of the loudspeaker unit (1) by adjusting the audio signal, wherein a signal feedback (7) is provided from the sound adjustment unit (5) to the VNC module (3), which transmits information about a current adjustment of the audio signal by the sound adjustment unit (5) to the VNC module (3), and wherein the VNC module (3) is configured to adjust the target level depending on the information about the current adjustment by the sound adjustment unit (5). [2] Control unit according to claim 1, wherein the current adjustment comprises an adjustment of a frequency-dependent level. [3] Control unit according to claim 2, wherein the sound adjustment unit (5) comprises an equalizer. [4] Control unit according to one of the preceding claims, wherein the information about the current adjustment includes a frequency-dependent level adjustment by the sound adjustment unit (5), wherein the module is designed to specify the target level in a frequency-dependent manner. [5] Control unit according to one of the preceding claims, wherein the VNC module (3) comprises a microphone (9) for compensating ambient noise, wherein the VNC module (3) is configured to use a sound level detected in the vehicle by means of the microphone (9) to specify the target level. [6] Control unit according to one of the preceding claims, wherein an input signal of the sound adjustment unit (5) is an output signal of the VNC module (3). [7] Method for generating an audio signal for a loudspeaker unit (1) in a vehicle, wherein a module (3) designed as a VNC module determines a target level of the audio signal for compensating ambient noise, and wherein a desired sound image of the loudspeaker unit (1) is generated by a sound adaptation unit (5) by adapting the audio signal, wherein a signal feedback (7) from the sound adaptation unit (5) to the VNC module (3) is used, which transmits information about a current adaptation of the audio signal by the sound adaptation unit (5) to the VNC module (3), and wherein the target level is set by the VNC module (3) depending on the information about the current adaptation by the sound adaptation unit (5). [8] Method according to claim 7, wherein an output signal is generated by the VNC module (3), which is adapted by the sound adaptation unit (5) and, after adaptation, is transmitted to the loudspeaker unit (1). [9] Method according to one of claims 7 to 8, wherein an input signal of the VNC module (3) is formed from an audio data stream and a volume setting adjustable by a user. [10] Method according to one of claims 7 to 9, wherein the VNC module (3) performs a vehicle speed-dependent compensation of a frequency-dependent level.

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